Micromechanical component as well as a method for producing a micromechanical component

ABSTRACT

A micromechanical component having a substrate beneath at least one structured layer, in the structured layer at least one functional structure being formed, a cap which covers the functional structure, between the cap and the functional structure at least one cavity being formed, and a connecting layer which connects the cap to structured layer, as well as a method for producing the micromechanical component. To obtain a compact and robust component, the connecting layer is formed from an anodically bondable glass, i.e. a bond glass, which has a thickness in the range of 300 nm to 100 μm, which may in particular be in the range of 300 nm to 50 μm.

FIELD OF THE INVENTION

[0001] The present invention relates to a micromechanical component, anda method for producing a micromechanical component.

BACKGROUND INFORMATION

[0002] German Published Patent Application No. 195 37 814 describes theconstruction of a sensor layer system and a method for the hermeticencapsulation of sensors in surface micromechanics.

SUMMARY OF THE INVENTION

[0003] A cost-effectively produced compact and long-term stablemicromechanical component characterized by a robust layer constructionand by a clear reduction of the area needed for the encapsulation.

[0004] The present invention concerns a cap that covers functionalstructures, the cap being connected with the structured layer with theaid of an anodically bondable glass or a bond glass. According to oneexemplary embodiment and/or exemplary method of the present invention,the connecting layer may be formed by the anodically bondable glasshaving a thickness in the range of 300 nm to 100 μm, especially athickness in the range of 300 nm to 50 μm. By the use of the anodicallybondable glass, a mechanically stable connection may be produced in asimple manner between the cap and the structured layer using a smallconnecting area. A considerable savings in area or a considerablyimproved wafer utilization may be achieved, particularly in massproduction where the micromechanical component may be formed more thanone thousandfold on one wafer or substrate.

[0005] According to another exemplary embodiment and/or exemplary methodaccording to the present invention, by choosing an anodically bondableglass having a thickness in the range of 300 nm to 100 μm, or especiallymaking it from a thicker glass wafer, one may cut the micromechanicalcomponents formed on a wafer into single pieces, using one single sawcut through the entire layer construction of the micromechanicalcomponent. This is possible because a customary saw blade for cuttingout micromechanical components from the wafer may also cut through theanodically bondable glass of the noted thickness without damaging thesaw blade or the component. Without the present invention, it may benecessary to make a saw cut down to the connecting layer using a firstsaw blade, to cut through the connecting layer using a second saw blade,and after that, to cut completely through the micromechanical component,or rather cut it into individual pieces, using the first saw bladeagain.

[0006] According to another exemplary embodiment and/or exemplary methodof the present invention, a bond glass may be used, which has aspecified ion concentration so as to be anodically bondable. Glasseswhich may be used as bond glasses include ones which have alkalisilicate and/or borosilicate.

[0007] According to yet another exemplary embodiment and/or exemplarymethod of the present invention, a terminal area may be provided forexternal contacting of the functional structures in the substrate of themicromechanical component. The terminal area may be electricallyinsulated from the substrate by an insulating frame formed by trenches.The terminal area may be provided directly next to or even under asupporting element in the substrate, in order to minimize, especiallyfor reasons of cost, the substrate area or volume required for themicromechanical component.

[0008] External contacting of the functional structures is achieved viaa funnel-shaped opening, provided in the cap, which expands away fromthe functional structures. In such an external contacting, the sawingsludge created during sawing, or rather the cutting into individualpieces of the micromechanical components from the wafer, may get intothe funnel-shaped access opening. Considerable effort may be needed toclean the funnel-shaped access opening of the sawing sludge. Any remainsof sawing sludge that are not washed out may lead to shunting, which maylead to the malfunctioning of the respective micromechanical component.

[0009] By dint of the terminal area for the external contacting of thefunctional structures being created in an exemplary manner according tothe present invention in the substrate, a method of plasma etching ortrench etching may be used, particularly with a substrate thickness inthe range of ca 80 μm to 150 μm, for example, ca 80 μm to 100 μm.Hereby, narrow, deep trenches may be produced for the formation of aninsulating frame, which may extend largely perpendicularly from theunderside of the substrate up to the functional layer. Selection of thesubstrate's thickness may be oriented to the required stability of themicromechanical component and to the maximum possible depth of thetrenches, down to which narrow trenches may be produced, for example, bytrench etching. These trenches, or rather the insulating frame formed bythe trenches, may be closed by a dielectric in the area on the undersideof the substrate, which electrically insulates the terminal area fromthe substrate while forming a part of the substrate.

[0010] According to another exemplary embodiment and/or exemplary methodof the present invention, a blind hole may be formed by etching, whichproceeds largely vertically through the substrate, the structured layer,and the connecting layer right up to the cap, where the floor of theblind hole is in the region of the cap, and the opening of the blindhole is on the side of the substrate opposite the functional structures.The blind hole or the passage at its floor area and on its wall areasmay be provided with a conducting layer, so that an electricalconnection may be made between the cap, the structured layer, and thesubstrate. The blind hole or the passage may be completely filled with afiller layer after production of the conducting layer. By putting theconducting layer at a definite electrical potential, at ground forexample, potential differences between the cap, the structured layer,and the substrate, and thus, potential interference voltages, may beavoided.

[0011] If the mechanical stability of the micromechanical component isnot sufficient, at least one supporting element may be provided betweenthe substrate and the cap, the supporting element may be formed byetching of the functional layer, and may be largely at the center of thecavity covered by the cap.

[0012] An exemplary method according to the present invention may beused to produce a micromechanical component in which the structuredlayer, which has functional structures, may be connected to a cap via aconnecting layer. The material of the connecting layer may be selectedin such a way that chemical bonding is brought about, by the applicationof an electrical voltage between the substrate and the cap of themicromechanical component, between the connecting layer and thestructured layer, as well as between the connecting layer and the capwhere a bond may be formed at the edge region of the cavity formedbetween the cap and the functional structures (anodic bonding). Forthis, at least the bonding region may be heated. The bonding of the capand the side of the bonding layer facing the cap may take place in afirst step, and the bonding between the structured layer and the side ofthe connecting layer facing the structured layer may take place in asecond step.

[0013] The bonding locations may be pretreated chemically and/ormechanically before anodic bonding in such a way that they have a slightsurface roughness quantifiable as approximately 40 nm or less. Finally,the component may posses a low topography, whereby, for example, thecomponent may be installed using the so-called flip-chip technique.

BRIEF DESCRIPTION OF THE DIAGRAMS

[0014]FIG. 1 shows a cross section of an exemplary embodiment of acomponent according to the present invention having a substrate, astructured layer, and a cap.

[0015]FIGS. 2 through 10 show an exemplary method according to thepresent invention for producing the component illustrated in FIG. 1.

DETAILED DESCRIPTION

[0016]FIG. 1 shows an exemplary embodiment of a component according tothe present invention, such as an acceleration sensor, in cross section.A structured layer 5, in which functional structures 7 and supportingstructures are formed, is positioned on a substrate 3. In the exemplaryembodiment, the functional structures 7 are formed in the structuredlayer 5 as meshing combs or interdigital structures having fixed anddeflectable electrodes. The supporting structures are formed by a frame15, which surrounds functional structures 7, and a supporting element 6,which is positioned inside frame 15 in the area of functional structures7, and may contribute to the mechanical stability of the layer system.In the exemplary embodiment of FIG. 1, only a supporting element 6 isillustrated, which is positioned between the two functional structures 7shown. However, depending on the required mechanical stability of thecomponent, provision may also be made, in the region of the functionalstructures, for no supporting element, a single supporting element 6, ora plurality of supporting elements spaced at a distance from oneanother. Expediently, the supporting element or supporting elements maybe positioned in such a way that the freedom of motion of functionalstructures 7 is not impaired.

[0017] An approximately planar cap 1 is connected to supportingstructures 6 and 15 of structured layer 5 via a connecting layer 2, andoverlaps functional structures 7. Supporting structures 6 and 15 aredeveloped raised in comparison with functional structures 7 (cf FIG. 3),and project above functional structures 7, for example, by about 4-10μm, so that cavities 7 a form in the region of functional structures 7,or open up between functional structures 7 and cap 1, respectively.

[0018] Alternatively or supplementary to the exemplary embodiment shownin FIG. 1, a depression may be provided in the region of the functionalstructures on the underside of the cap, i.e. on the side of the capfacing functional structures 7, so that the depression forms the cavityor cavities 7 a above functional structures 7 in whole or in part (notshown).

[0019] Connecting layer 2 is removed in the region of functionalstructures 7, so that the height of the gap H of cavities 7 a becomescorrespondingly greater. Expediently, the height of the gap H ofcavities 7 a may be such that a destructive deflection of functionalstructures 7 in the vertical direction, i.e. in the z direction, isprevented. The total gap range of cavities 7 a in the lateral directionmay lie between about 100 and 500 μm. However, gap widths up to severalmm are also possible.

[0020] At first ends 6 a and 15 a, of supporting element 6 and of frame15, associated with cap 1, connecting areas 4 for connecting 5 toconnecting layer 2 are formed. Connecting areas 4 may have a width ofless than 150 μm and a high surface quality or rather, a low surfaceroughness, which may amount to approximately 40 nm or less. Supportingelement 6 and frame 15 are connected at their other ends 6 b and 15 b tosubstrate 3.

[0021] Between substrate 3 and structured layer 5 printed circuit traces13 are provided which may be used for the external contacting offunctional structures 7. Printed circuit traces 13 are placed closelyunderneath functional structures 7, and 12 run through duct areas 6 cand 15 c of supporting structures 6 and 15, two sacrificial layers 16and 17 (see FIG. 2) insulating printed circuit traces 13 from supportingstructures 6 and 15.

[0022] In addition, for external contacting of functional structures 7,a terminal area 14 is formed in substrate 3, for the most part directlynext to functional structures 7, which is located at upper side 3 b ofsubstrate 3 facing structured layer 5, in direct contact with contactreed 18 of printed circuit traces 13. Terminal area 14 is completelysurrounded by trenches 14 a, which form an insulating frame. Trenches 14a extend from the substrate's underside to the substrate's upper side,so that terminal area 14 formed thereby may be electrically insulatedfrom substrate 3. Trenches 14 a may have a high aspect ratio, i.e. greatdepth and a slight lateral dimension size. A metallic coating 12 isapplied to terminal area 14 on its backside 3 a of substrate 3 facingaway from structured layer 5, which may form a printed circuit trace anda contact pad for fastening bonding wire, via which an externalelectrical connection to functional structures 7 is produced. Metalliccoating 12 is insulated from substrate 3 at backside 3 a of substrate 3by a dialectric layer 22.

[0023] Metal coating 12, and thus the printed circuit trace and thecontact pad may extend from terminal area 14 horizontally in thedirection of functional structures 7, whereby the wafer area andsubstrate area, respectively, required for the production of thecomponent may be reduced in a cost-saving manner.

[0024] According to one exemplary embodiment (not shown), terminal area14 for external contacting of functional structures 7 may be producedlargely centrically below supporting element 6. This may lead to savingsin wafer area and substrate area required for producing the component,which is consistent with a cost-saving reduction in volume of thecomponent. Packing density may also be increased.

[0025] Furthermore, between substrate 3, structured layer 5, and cap 1,a conductive connection 8 is provided, in order to avoid differences inpotential between the substrate and cap 1. Conductive connection 8includes a blind hole or rather, a passage 9, which extends outside theregion of printed circuit traces 13 through substrate 3, frame 15 andinto a part of cap 1. A conductive layer 10, for example a metalliclayer, which is positioned on the bottom and the wall surfaces 9 a ofpassage 9, connects substrate 3, structured layer 5 and cap 1. A fillerlayer 11 closes passage 9 on the backside 3 a of substrate 3, and evensout the topography.

[0026]FIGS. 2 through 10 describe an exemplary method for producing thecomponent illustrated in FIG. 1. The layer construction of the componentis shown in FIG. 2 as it looks before the depth structuring ofstructured layer 5. On substrate 3, which may be made of monocrystallinesilicon, a first sacrificial layer 16 is applied which may be made, forinstance, of one or more SiO₂ layers. On first sacrificial layer 16printed circuit traces 13 are deposited, made of polycrystallinesilicon, which may be sufficiently strongly doped for the purpose ofachieving as high as possible a conductivity. First sacrificial layer 16is prestructured before the application of the printed circuit traces13, a contact opening for correspondingly formed contact reed 18 beingetched into first sacrificial layer 16 for each of the printed circuittraces 13. Each of contact reeds 18 borders directly on substrate 3 andis directly connected to terminal area 14 formed later in each case insubstrate 3. The production of the terminal areas described and theirrespective external contacting (not illustrated) may be carried out inthe same way as the production and external contacting of the explicitlyillustrated terminal area 14.

[0027] A second sacrificial layer 17, similarly made of of SiO₂, isdeposited on printed circuit traces 13, and functions as an insulatinglayer. CVD [chemical vapor deposition] methods may be used for theproduction of the second sacrificial layer 17, such as when usingtetraethyl orthosilicate (TEOS). Then, on second sacrificial layer 17, athin polysilicon starter layer 5 a is deposited, i.e. a polycrystallinesilicon layer having the function of a seeding or nucleating layer. Onstarting polysilicon layer 5 a a polycrystalline silicon layer, whichrepresents the subsequently formed structured layer 5, is deposited,using an epitaxial method, the starting polycrystalline layer merginginto the upper polycrystalline layer. The surface of upperpolycrystalline layer 5 is leveled in a further process step. Achemical-mechanical polishing process (CMP) may be used to achieve asurface roughness which allows the surfaces to connect or anodicallybond well with connecting layer 2 by the application of a voltagedifference. The surface roughness in this case may amount to ca 2 nm toca 50 nm.

[0028] Sacrificial layers 16 and 17 are expediently structured beforethe deposition of starting polysilicon layer 5 a. In this case, firstand second sacrificial layers 16 and 17 are partially or completelyremoved in regions 16 a, in which supporting structures 6 and 15 areformed in a later process step, so that supporting structures 6 and 15are directly connected to the substrate. In second sacrificial layer 17,contact openings 17 a are formed for contacting functional structures 7to printed circuit traces 13.

[0029] As shown in FIG. 3, an oxide mask 20 is deposited on connectingsurfaces 4 by a CVD method, connecting surfaces 4 being located in thearea of supporting structures 6 and 15 which are formed later. Oxidemask 20, precipitated from the gas phase, is used as a passivating layeron account of its good Si/SiO₂ selectivity, and ensures that connectingsurfaces 4 are not attacked by a later plasma etching step or achemical-mechanical polishing process (CMP). Using a dry etching methodor an additional CMP step, planar recesses are etched or formed inregions 7 of structured layer 5, in which functional structures 7 arestructured later. Oxide mask 20 is subsequently removed.

[0030] Alternatively or in supplement to the exemplary method of FIG. 3,one or more recesses (not illustrated) may be produced at the undersideof the cap, for the complete or partial formation of the cavity abovethe functional structures, for example, by plasma etching.

[0031] In the exemplary process step described above, supportingstructures 6 and 15 are prestructured opposite functional structures 7,with respect to their height (and possibly with respect to their width),by thinning structured layer 5 in the areas of functional structures 7by a specified quantity.

[0032] Alternatively, in order to make supporting structures 6 and 15higher, a connecting layer may be used having a correspondingly greaterthickness dimension (case not shown).

[0033] If one or more recesses may be provided at the underside of thecap, they may be structured in such a way that the recess(es) has(have)one or more supporting elements, which complement(s) one or moresupporting elements of structured layer 5 (not illustrated).

[0034] In a further exemplary process step shown in FIG. 4, functionalstructures 7 and supporting element 6 are structured using trenchetching. Second sacrificial layer 17 and in part also first sacrificiallayer 16 are removed below functional structures 7 using a gas phaseetching method, so that deflectable structures are created.

[0035] The hermetically sealed encapsulation of the component or rather,the sensor layer system, is performed in an exemplary central step, asshown in FIG. 5. Cap 1, which may be made of monocrystalline silicon, ishere chemically bonded to connecting surfaces 4 of supporting structures6 and 15, via connecting layer 2.

[0036] Connecting layer 2 may be made of a silicate glass about 10-50 μmthick, which may be produced by chemical and/or mechanical treatmentfrom a thicker silicate glass wafer, for example, 500 μm in thickness.The silicate glass has a specified concentration of monovalent orhigher-valent cations, such as Na⁺ or B³⁺, and a correspondingconcentration of weakly bound oxygen atoms. Alkali silicates andborosilicates may be particularly suitable.

[0037] In order to be able to produce a high surface quality for thepurpose of an optimum joint between cap 1 and connecting layer 2, cap 1is chemically-mechanically polished on its side facing connecting layer2. After the CMP step, the surface roughness is typically under 2 nm.Then, cap 1 is connected in a planar manner to connecting layer 2 by theapplication of a voltage difference between the cap and connecting layer2, typically ca −150 to−1000 V, cap 1 being grounded. During theconnecting step, a raised temperature of about 350-450° C. mayadditionally act on connecting layer 2, in order to increase themobility of the metal or boron cations. The reduced cation concentrationmay be compensated for by a supplementary temperature action.Alternatively or in supplement, after connecting cap 1 to connectinglayer 2, the supply voltage is reversed so as to compensate for thereduced concentration of cations that has been created at the boundarybetween connecting layer 2 and cap 1.

[0038] Alternatively, connecting layer 2 may be deposited on cap 1 infused form, the melting or softening temperature, respectively, being ina range of 600-800° C., depending on the kind of silicate glass used. Atthis temperature range, chemical bonding between cap 1 and connectinglayer 2 may also take place. After solidification, connecting layer 2may be processed as described below.

[0039] After the bonding of cap 1 to connecting layer 2, connectinglayer 2 is ground down roughly mechanically, or rather thinned downaccording to the above first or second alternative on the side facingconnecting surface 4, and is subsequently polished in a CMP step inorder to produce a good joint with connecting surfaces 4 of structuredlayer 5.

[0040] After this processing, connecting layer 2 has a thickness ofabout 10-50 μm, and a surface roughness of 2 nm or less.

[0041] Alternatively, the Connecting layer may be deposited bysputtering of silicate glass, particularly using electron beamsputtering. Before that, the cap is oxidized thermally, whereby a ca 1to 2 μm layer of silicon oxide layer is formed on which the connectinglayer is deposited by sputtering. The silicon oxide layer improves theelectrical voltage resistance during anodic bonding. For a connectinglayer (alkali or borosilicate) formed by sputtering, layer thicknessesmay be in the range of about 300 nm to 2 μm.

[0042] Connecting layer 2 is removed in the area of functionalstructures 7 in all three alternatives recited above, or is structuredso as to increase the size of gap height H of cavities 7 a.

[0043] Connecting layer 2 is also removed in the region of connectingpassage 9, formed later, of conductive connection 8. In a furtherprocess step, the bonding of connecting surfaces 4 of structured layer 5to connecting layer 2 takes place. Connecting surfaces 4 and connectinglayer 2 are adjusted to each other and chemically connected (anodicbonding) by the supply voltage applied and/or under the action oftemperature. For this step, a lower voltage is applied to cap 1 comparedto that of the bonding of cap 1 to connecting layer 2, to preventexcessive deflection of functional structures 7 as a result of thebonding voltage. Typically, this may be −100 V at cap 1, substrate 3being grounded.

[0044] During the encapsulation, a gas having a pressure between 1 mbarand 1 bar may be enclosed in cavities 7 a, the damping of functionalstructures 7's movement being determined by the pressure. In asupplementary way, after encapsulation, a liquid may also be conveyedinto cavities 7 a via an opening that may be closed again, its viscositydetermining the degree of the damping, or also a gas, or even a furthergas.

[0045] The basic doping Of n-doped substrate 3 may be typically greaterthan 5★10¹⁵/cm³, and the ohmic resistance less than ca 1 Ohm★cm(low-resistance). The doping of n-doped function layer 5 isapproximately 10¹⁷/cm³ to 10¹⁹/cm³, which makes possible alow-resistance external contact to functional structures 7.

[0046] Using the anodic bonding method described above, a hermeticallysealed connection is produced, on the one hand, between cap 1 andconnecting layer 2 and, on the other hand, between connecting layer 2and connecting surfaces 4 or structured layer 5. In this manner,relatively small connecting surfaces 4 are needed. For example, thewidth of the connecting surfaces is only about 30 to 150 μm.

[0047] After the connection of cap 1 to connecting surfaces 4, therefollows mechanical grinding back of backside 3 a of substrate 3 (cf FIG.6). This may take place in several steps: First backside 3 a ofsubstrate 3 is ground down coarsely abrasively, using a diamond grindingdisk of large grain size, and subsequently using a diamond grinding diskof smaller grain size having correspondingly less material removal.Alternatively, the grinding down may also be performed in a single step.After finishing, the surface roughness amounts to about 0.1-1 μm, andthe depth of crystal dislocation comes to about 3-5 μm.

[0048] The crystal dislocations are removed by a CMP process and thesurface quality is thereby further improved. The material removal hereamounts to about 10 μm. The crystal dislocations in substrate 3 mayalternatively be removed by so-called spin etching. The material removalhere typically amounts to 5 to 10 μm. After subsequent CMP levelingthere may still be a material removal of typically 3 μm.

[0049] The residual thickness K of substrate 3 is selected in such a waythat the static stability of the layer system is ensured, supportingelements 6 considerably improving the static stability. One may dowithout the supporting elements particularly when the gap widths aresmall. Typically, residual thickness K of substrate 3 may be about80-150 μm.

[0050] In a further process step (cf FIG. 6) trenches 14 a are formedfor contact area 14 by trench etching. Furthermore, passage 9 is formedby a deep-etching method, passage 9 extending through substrate 3,structured layer 5 and partially into cap 1.

[0051] As illustrated in FIG. 7, conductive layer 10 is applied tobottom surface and wall surfaces 9 a of passage 9, or rather, blindhole, by being deposited on the backside 3 a of substrate 3. Conductivelayer 10, which may be a metallic layer, for example, produces a lowohmic connection of substrate 3 to cap 1 and structured layer 5.Subsequently, a filler layer 11 is introduced into passage 9, or theblind hole, which closes passage 9 and evens out the surface topography.Filler layer 11 may be a silicon oxide layer which may be produced by aso-called spin-on method or by introducing and hardening a fillermaterial containing silicon dioxide.

[0052] As shown in FIG. 8, filler layer 11 is etched back using a plasmaetching method. Subsequently, on backside 3 a of substrate 3 is removedby a wet-chemical process. Here care should be taken that conductivelayer 10 is completely removed in the region of trenches 14 a, and thatin the region of passage 3 there is not excessively much overetching, sothat no undesired topographies form.

[0053] According to FIG. 9, dielectric layer 22 is deposited on backside3 a of substrate 3 by a CVD method. Dielectric layer 22 is used asinsulating layer and insulates subsequently deposited metallic coating12 from substrate 3. Near terminal area 14, a contact opening 23 isformed in dielectric layer 22, for the external contacting of terminalarea 14. Subsequently, as shown in FIG. 10, metallic layer 12 isdeposited on dielectric layer 22 and on terminal area 14 via contactopening 23, and may be structured wet-chemically to a printed circuittrace or to a terminal, the terminal pad extending, for example, in thedirection of the center of the component. Thereby the substrate areaneeded for the production of the component and the latter's volume maybe reduced, at savings in cost.

[0054] The sensor or actuator structures may be integrated together withan electronic evaluation circuit (not shown) into cap 1 and/or intostructured layer 5.

[0055] The exemplary component described above may stand out as having acompact and robust design, which may permit the integration of aplurality of functional structures, and, at the same time, may permitadequate freedom of movement of the functional structures.

[0056] The exemplary method described above makes possible theproduction of a plurality of components requiring hermetically sealedencapsulation. In this manner, the effort or expenditure required forencapsulation and connecting surfaces may be reduced to a minimum.

[0057] The list of reference numerals is as follows:

[0058]1 Cap

[0059]2 connecting layer

[0060]3 substrate

[0061]3 a backside of substrate

[0062]3 b upper side of substrate

[0063]4 connecting surface

[0064]5 structured layer having functional structures of a sensor

[0065]5 a starting polysilicon layer

[0066]6 supporting element

[0067]6 a first end of supporting element (supporting element)

[0068]6 b second end of supporting element

[0069]6 c passage of supporting element

[0070]7 deflectable functional structures of the sensor in structuredlayer 5

[0071]7 a cavity

[0072]8 conductive connection

[0073]9 passage

[0074]9 a wall surface

[0075]10 conductive layer

[0076]11 filler layer

[0077]12 metallic layer

[0078]13 printed circuit traces made of low-resistance polysilicon

[0079]14 terminal area

[0080]14 a trenches or insulating trenches

[0081]15 frame

[0082]15 a first end of frame

[0083]15 b second end of frame

[0084]15 c passage in frame

[0085]16 first sacrificial layer

[0086]16 a areas of first sacrificial layer

[0087]17 second sacrificial layer

[0088]17 a contact openings of second sacrificial layer

[0089]18 contact reed

[0090]20 oxide mask

[0091]21 recess forming a part of cavity 7 a

[0092]22 dielectric layer

[0093]23 contact opening of dielectric layer

[0094] H gap height determined by total thickness of connecting layer 2and depth of recess 21

[0095] K remaining thickness of substrate 3.

What is claimed is:
 1. A micromechanical component comprising: asubstrate; at least one structured layer on the substrate, wherein atleast one functional structure is formed in the at least one structuredlayer; a cap covering the functional structure, wherein at least onecavity is formed between the cap and the at least one functionalstructure; and a connecting layer to connect the cap with the structuredlayer, wherein the connecting layer is formed by an anodically bondableglass having a thickness in a range of 300 nm to 100 μm.
 2. Themicromechanical component of claim 1, wherein the anodically bondableglass has a defined ion concentration.
 3. The micromechanical componentof claim 1, wherein at least one terminal area is formed in thesubstrate to externally contact the at least one functional structure,the at least one terminal area being electrically insulated from thesubstrate by an insulating frame formed by trenches.
 4. Themicromechanical component of claim 3, wherein the terminal area isformed by a part of the substrate, the substrate being doped such thatthe terminal area is low-resistance.
 5. The micromechanical component ofclaim 1, wherein, between the substrate and the cap, at least onesupporting element is provided in the at least one structured layer. 6.The micromechanical component of claim 5, wherein the substrate has athickness between ca 80 μm and 150 μm.
 7. The micromechanical componentof claim 5, wherein the terminal area is positioned one of next to theat least one functional structure and below the at least one supportingelement in the substrate.
 8. The micromechanical component of claim 1,wherein the micromechanical component includes the substrate and the atleast one structured layer, which is provided on at least one part ofthe substrate and is covered at least partly by the cap, and aconductive connection is provided between the cap and the substratewhich extends all the way through the at least one structured layer andis positioned near a frame structure of the at least one structuredlayer.
 9. The micromechanical component of claim 8, wherein theconductive connection is formed by a passage on whose bottom surface andwall surfaces a conductive layer is deposited, the at least one of thepassage and the conductive layer being covered by at least oneinsulating layer on a side of the substrate opposite the at least onestructured layer.
 10. The micromechanical component of claim 3, whereinthe terminal area is in contact with at least one printed circuit traceon a side of the substrate facing the at least one structured layer, andis furnished with a metallic layer on a side of the substrate oppositethe at least one structured layer, at least one insulating layer beingprovided between the metallic layer and the substrate.
 11. Themicromechanical component of claim 1, wherein the cap, the substrate,and the at least one structured layer are made at least partially of asame material.
 12. A method for producing a micromechanical componenthaving at least one structured layer, in which at least one cap isconnected to regions of the at least one structured layer and covers theat least one structured layer at least partially, the method comprising:bonding the cap to the regions of the at least one structured layerusing a connecting layer that produces a chemical bond when at least oneof an electrical voltage and a temperature is applied to it, thechemical bond occurring between the connecting layer and at least one ofthe regions of the at least one structured layer and the cap.
 13. Themethod of claim 12, wherein the bonding of the cap with the regions ofthe at least one structured layer includes: chemically bonding the capto the connecting layer; and chemically bonding the regions of the atleast one structured layer to a side of the connecting layer facing theat least one structured layer while, at approximately the same time,enclosing at least one of a gas and vacuum in at least one cavity formedbetween the cap and the at least one structured layer.
 14. The method ofclaim 12, wherein the connecting layer includes at least one of a glassand a glass-type material having a specified ion concentration.
 15. Themethod of claim 12, wherein the regions of the at least one structuredlayer have connecting surfaces, the connecting surfaces and a side ofthe cap facing the connecting layer being at least one of chemically andmechanically treated before the bonding, so that they have acomparatively slight surface roughness.
 16. The method of claim 12,wherein the connecting layer is treated at least one of chemically andmechanically before bonding to the connecting surfaces of the at leastone structured layer, so that it has a slight surface roughness.
 17. Themethod of claim 12, wherein the connecting layer is formed from at leastone of: a glass wafer by reducing its thickness to about 10 to 50 μm; asilicate glass fusion; and by sputtering on a glass layer.
 18. Themethod of claim 17, wherein the silicate glass fusion includes at leastone of alkali silicate and borosilicate.
 19. The method of claim 17,wherein the glass layer is in the range of 300 nm to 2 μm.
 20. Themicromechanical component of claim 1, wherein the thickness of theanodically bondable glass is in the range of 300 nm to 50 μm.
 21. Themicromechancial component of claim 2, wherein the anodically bondableglass includes at least one of alkali silicate and borosilicate.
 22. Themicromechanical component of claim 5, wherein the at least onesupporting element is positioned largely in a center of the cavity. 23.The micromechanical component of claim 6, wherein the substrate has athickness of ca 80 μm to 100 μm.
 24. The micromechanical component ofclaim 9, wherein the at least one of the passage and the conductivelayer is covered by at least one insulating layer on a side of thesubstrate opposite the at least one structured layer.
 25. Themicromechanical component of claim 11, wherein the same material issilicon.
 26. The micromechanical component of claim 25, wherein the capand the substrate are made of monocrystalline silicon and the at leastone structured layer is made of polycrystalline silicon.
 27. The methodof claim 14, wherein the connecting layer includes at least one of analkali silicate or a borosilicate.
 28. The method of claim 15, whereinthe slight surface roughness is 2 to 40 nm.
 29. The method of claim 16,wherein the slight surface roughness amounts to 2 nm or less.